JS: remove an unneeded abstract method declaration, the implemented interface already defines it
JS: remove an unneeded abstract method declaration, the implemented interface already defines it

Signed-off-by: Harvey Harrison <eadbd6b462bf3c97df0300a934c12bc2e5d1fe51@gmail.com>

jaamsim/jaamsim,jaamsim/jaamsim,jaamsim/jaamsim,jaamsim/jaamsim